> On 31 Oct 2024, at 14:51, Igor Khanin <i...@khanin.biz> wrote:
> 
> Greetings,
> 
> I hope this is the right place to post this. I'm looking for advice as well 
> as any historical context I can get.
> 
> The documentation states that the `QTextFormat::LayoutDirection` text format 
> property is both a paragraph and a character property. When set on a block 
> format, it indeed affects the block's base direction via 
> `QTextBlock::textDirection`. However when set on a character format, to the 
> best of my understanding it appears to have no effect whatsoever. I'd expect 
> it to have some sort of similar impact on the BiDi algorithm - perhaps 
> overriding the directional character type of the character to be L or R, or 
> maybe making a sequence of characters with the same property value behave as 
> if they were an isolation run, or some such. But that can't obviously happen 
> currently, as `QBidiAlgorithm` has no access to any formats and finishes its' 
> work before character formats are resolved anyway.
> 
> This appears to be the case since Scribe was first released back in Qt 4, or 
> at the very least predates the current Git history. So my question is why 
> then the documentation says that? Was there an intention to implement some 
> behavior that then never happened?
> 
> Furthermore - would it make sense for this property to start _actually_ doing 
> anything on individual characters? I have a hacky POC, but don't want to 
> waste my own and other's time if this is something that would be considered 
> too niche or disruptive.
> 
> Best,
> Igor

Hi Igor,

It’s the right place to post this, but it would help to understand what you are 
trying to achieve with an implementation of layout direction on as a character 
format. My understanding of the subject doesn't go very deep (and I can’t say 
if the documentation is wrong or simply misleading - perhaps it’s a read-only 
attribute), but to change layout direction within a block, you’d usually insert 
Unicode control characters into your text.

Volker


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